A20B-3300-0635 Fanuc PCB Board A20B33000635 A2OB-33OO-O635

A20B-3300-0635 | FANUC Axis Card A1 — Servo Axis Control Module / A20B-3300-063x Family / CNC Drive Interface

Axis Card — What It Is and What It Does

An "Axis Card" in FANUC CNC architecture is a dedicated plug-in module that provides the servo axis interface between the CNC's main CPU board and the servo drive amplifiers. It is not the main CPU, nor a memory module — it is the specialised processor card responsible specifically for servo axis communication and control.

The A20B-3300-0635 (Axis Card A1) performs these core functions:

FSSB communication master: Generates the fibre-optic FSSB (Fibre-optic Servo Serial Bus) signals that command the servo drive amplifiers. At each interpolation cycle, this card transmits the position command to each axis drive and receives the encoder feedback — the cycle that closes the position loop for every controlled axis.

Servo coordinate processing: The position command for each axis must be computed relative to the servo's current position, within the CNC's coordinate system. The axis card handles the arithmetic that translates the CNC's interpolation result into the per-axis drive command.

Digital current control interface: The FSSB data stream from the axis card includes not only position commands but also the parameter data for the servo drive's current control loops — gain values, HRV2/HRV3 mode settings, and protection thresholds that define the drive's dynamic behaviour.

Key Product Information

A20B-3300-063x Axis Card Family

The A20B-3300-063x range is a defined Axis Card module family, with multiple type designations:

The "A1, A2, A3" type designations represent different capability levels or platform-specific configurations within this Axis Card family. The A1 (0635) is the base type — the standard configuration that serves the foundational servo axis control requirement.

Application Scenarios

Axis card fault on FANUC CNC: A FANUC CNC develops FSSB communication alarms on specific axes. The axis card A1 (A20B-3300-0635) is identified as the fault. Replacement restores FSSB servo communication.

CNC axis control module maintenance: A FANUC CNC system undergoing electronics maintenance has its axis card replaced. The A20B-3300-0635 A1 type is confirmed from the installed card's label.

FAQ

Q1: What is the difference between Axis Card A1 (A20B-3300-0635) and Axis Card A2 (A20B-3300-0638)?

The A1 type is the base configuration of the 063x Axis Card family. The A2 type (A20B-3300-0638) is confirmed for Series 0i-D (0i-TD/0i-MD) applications with up to 4 axes, HRV3/HRV2 servo control. The A1 type serves a different platform configuration within the same axis card architecture.

Q2: How many servo axes does A20B-3300-0635 support?

The axis count supported by A20B-3300-0635 depends on its specific FSSB channel configuration. Confirm the axis count from the applicable FANUC CNC hardware manual for the specific system in which A20B-3300-0635 is installed.

Q3: Does replacing A20B-3300-0635 require servo parameter re-entry?

No. Servo parameters reside in the CNC's main memory — not in the axis card. After fitting a replacement A20B-3300-0635, the CNC reloads the existing parameters and re-establishes FSSB communication with all servo drives. Verify normal servo response before returning to production.

Q4: Is A20B-3300-0635 compatible with HRV3 servo control?

Confirm from the applicable FANUC maintenance manual whether the A1 type axis card supports HRV3. The A2 type (0638) is confirmed for HRV3/HRV2. Whether the A1 type includes HRV3 capability depends on its specific hardware specification.

Q5: How do I confirm A20B-3300-0635 is the correct axis card for my CNC?

Read the part number from the installed card's label. If it reads A20B-3300-0635, this is the confirmed replacement. Cross-reference with the spare parts table in the applicable FANUC CNC maintenance manual.